Most individuals buy and use a hair shampoo for its cleansing properties. In addition to clean hair, the consumer also desires sufficiently-conditioned hair that holds a preset configuration. However, present-day hair shampoos generally are formulated with highly-effective synthetic surfactants, like anionic surfactants, that primary clean, as opposed to conditioning, the hair. Therefore, it is not surprising that hair shampoos usually neither help detangle wet hair nor impart any residual hair conditioning benefits to dry hair, such as the manageability or styleability of hair sets.
Consequently, after shampooing, the hair normally is left in a cosmetically-unsatisfactory state because an anionic surfactant-based hair shampoo composition not only removes all of the dirt and soil from the hair, but also removes essentially all of the sebum that is naturally present on the surface of the hair fibers. Therefore, the properties of anionic surfactants that effectively cleanse the hair also serve to leave the hair in a cosmetically-unsatisfactory condition. In general therefore, shampooing the hair with a hair shampoo composition including anionic surfactants, leaves the hair, after rinsing with water, with an undesirable harsh, dull and dry touch or feel, usually called "creak".
As a result, thoroughly cleansed hair is extremely difficult to comb, in either the wet or dry stage, because the individual hair fibers tend to snarl, kink and interlock with each other. In addition, incompletely dried hair, such as hair dried with a towel, has poor brushing properties. Then, after complete drying, the hair does not set well, and the combing or brushing property of the dried hair remains poor. The dried hair also has undesirable electrostatic properties in a low humidity atmosphere that cause the hair to "fly away", thereby further reducing the brushing property of the hair. The unsatisfactory combing or brushing property of freshly-shampooed hair also causes hair damage, such as split ends or hair breakage. In addition, the natural luster and resiliency of the hair is reduced.
Accordingly, freshly-shampooed hair usually requires a post-shampoo hair treatment with a conditioning composition to improve the unsatisfactory physical and cosmetic condition of the hair. A conditioning composition normally is applied separately from the hair shampoo, and usually is a rinse or a cream-like lotion containing a cationic compound. Therefore, investigators have sought hair shampoo compositions that both cleanse the hair and leave the hair in a cosmetically-satisfactory state, such that the subsequent treatment with a conditioner composition can be avoided.
Consequently, investigations were directed at providing a composition that behaves both as a shampoo and as a hair conditioner. However, the resulting shampoo-conditioner compositions possessed several disadvantages. For example, it is known in the art that anionic surfactants are suitable hair cleansers, and that, in many instances, cationic surfactants and cationic polymers are suitable hair conditioners. However, the major difficulty encountered by investigators is the inherent incompatibility between an anionic surfactant and a cationic surfactant or cationic polymer. Consequently, contact between the anionic surfactant and the cationic surfactant or cationic polymer either produces an intractable precipitate that forms immediately, or causes an interaction between the anionic and cationic components that significantly reduces their respective cleansing and conditioning properties. The reduction in cleansing and conditioning effectiveness also is observed in compositions wherein the anionic and cationic components do not precipitate from the composition but remain in solution or in a suspended state. This incompatibility between an anionic compound and a cationic compound is well recognized by workers skilled in the art. For example, Sagarin in Cosmetics, Interscience Publishers, Inc., New York, p. 538, 1956, states that anionic and cationic compound cannot be used in combination because they react to form insoluble salts. Thus, in practice, consumer needs traditionally have been met by applying a nonsubstantive, anionic surfactant-based shampoo to the hair to cleanse the hair, then rinsing the hair, followed by applying a conditioner composition including a substantive cationic compound to the hair to condition the hair.
While numerous shampoos including a substantive cationic hair conditioner have been disclosed, such shampoos have not been totally satisfactory because of the compatibility problems between anionic cleansing surfactants and cationic conditioning compounds. This compatibility problem has caused workers in the field to examine other surfactants such as nonionics, amphoterics and zwitterionics as a total or partial replacement for the anionic cleansing surfactant. However, the nonionic, amphoteric and zwitterionic surfactants are inferior cleansing surfactants compared to the anionic surfactants.
To avoid the anionic-cationic compatibility problems inherent in a conditioning shampoo that includes an anionic cleansing surfactant and a substantive cationic conditioning compound, to increase the degree of conditioning imparted to the hair, and to maintain the cleansing efficiency of the hair shampoo, investigators sought other classes of compounds that were substantive to the hair and that imparted improved conditioning properties to the hair. These compounds usually are water-insoluble compounds and are nonionic in character. Exemplary compounds include the silicone conditioning agents, the hydrocarbon conditioning agents, the fatty esters and the fatty alcohols including about 8 to about 22 carbon atoms. However, although these compounds avoided the anionic-cationic compatibility problems, these compounds presented the problems of formulating a stable composition that resisted phase separation over the normal life of the product, that effectively delivered the conditioning agent to shampooed hair, and that generated a sufficient foam level for consumer acceptance.
Shampoo-conditioner compositions including silicones have been disclosed in several patents, including U.S. Pat. No. 2,826,551 to Green; U.S. Pat. No. 3,964,500 to Drakoff; U.S. Pat. No. 4,364,837 to Pader; British Pat. No. 849,433 to Woolston; U.S. Pat. No. 4,741,855 to Grote, et al.; U.S. Pat. Nos. 4,788,006 and 4,902,499 to Bolich, Jr. et al. and U.S. Pat. No. 4,704,272 to Oh et al.
A particularly difficult problem encountered in silicone-containing conditioning shampoos is maintaining a dispersed, insoluble silicone material suspended in stable form, while retaining the cleansing and conditioning performance of the conditioning shampoo product. A variety of materials have been proposed for inclusion in silicone-containing conditioning shampoos for purposes of thickening and stabilization such as xanthan gum, long chain acyl derivatives, long chain amide oxides, and long chain alkanolamides, as disclosed in U.S. Pat. Nos. 4,788,006; 4,704,272; and 4,741,855.
Therefore, because hair shampoo compositions are predominantly anionic in character, the incorporation of a substantive cationic compound into an anionic shampoo composition is difficult because of the inherent incompatibility between anionic and cationic surfactants. Similarly, the incorporation of a water-insoluble conditioning agent into an anionic shampoo composition is difficult because of the inherent phase instability between the aqueous-based shampoo and the water-insoluble conditioning agent. Nevertheless, a conditioning shampoo composition is desirable because of the convenience such a combination product offers to the consumer. In such a conditioning shampoo composition, the anionic surfactant acts to rid the hair and scalp of dirt, surface film, debris, and the like, while the water-insoluble conditioning compound deposits on the hair to provide conditioning benefits, such as manageability, shine and texture.
Until the composition and method of the present invention, it has proven very difficult to provide a stable hair conditioning shampoo composition because of the inherent chemical incompatibility between cationic and anionic surfactants, and because of the phase instability of an aqueous composition including a water-insoluble conditioning agent. In accordance with an important feature of the present invention, a particular class of anionic emulsifying surfactants and a water-insoluble conditioning agent are incorporated into a conditioning shampoo composition wherein the composition effectively resists phase separation, and wherein the water-insoluble conditioning agent is effectively deposited on the shampooed hair. The conditioning shampoo, including both an anionic cleansing surfactant and a water-insoluble nonionic conditioning agent, therefore, is utilized to clean the hair and, essentially simultaneously, to impart conditioning properties to the hair.
In accordance with an important feature of the present invention, an anionic emulsifying surfactant depicted by general structural formula (I), e.g., a carboxylated surfactant, is present not only to help cleanse the hair, but also to act, in conjunction with the polyhydric compound, as an emulsifying composition to emulsify the water-insoluble conditioning agent. Furthermore, it has been found that a phase stable conditioning shampoo is provided by the method of preparing the conditioning shampoo of the present invention. In particular, by first preparing a gel including the anionic emulsifying surfactant depicted by general structural formula (I), the polyhydric compound and the water-insoluble conditioning agent, followed by admixing the gel with an aqueous solution of the anionic cleansing surfactant and the suspending agent, a stable emulsion that resists phase separation and that effectively cleanses and conditions the hair, essentially simultaneously, is provided.
Other investigators have disclosed using a preblended gel to incorporate a water-insoluble compound into an aqueous emulsion. For example, Yamada et al., in U.S. Pat. No. 4,379,755, disclose a gel composition including a hydrophilic sucrose fatty acid ester, a polyhydric alcohol and an oil, that provides a phase stable emulsion after dilution with water. Yamada et al. teach the emulsification of a water-insoluble compound utilizing a blend of a nonionic sucrose fatty acid ester and a polyhydric alcohol. Yamada et al. do not teach or suggest solubilizing a water-insoluble compound in a blend of an anionic emulsifying surfactant depicted by general structural formula (I) and a polyhydric alcohol, then diluting the preblended gel with an aqueous solution of a suspending agent and anionic cleansing surfactant to provide an emulsified composition that effectively resists phase separation and that essentially simultaneously cleanses and conditions the hair.
The need for an effective and stable conditioning shampoo composition that cleanses the hair and conditions the hair, i.e., renders the hair more manageable, in a single hair treatment has long been recognized in the art. Accordingly, although conditioning compositions for application to previously-shampooed hair are well known, only recently have conditioning shampoo compositions become available. For example, some conditioning shampoo compositions are specially formulated for mildness, and accordingly low detergency, in order to leave a portion of the natural oils on the hair shaft. However, hair treated with this type of composition becomes greasy, dirty looking and dirty feeling relatively quickly.
Another difficulty encountered in preparing this type of conditioning shampoo composition has been achieving a stable composition without destroying the delicate balance of conditioning, cleansing, consumer appeal, esthetic properties and other functional properties. Surprisingly and unexpectedly, although a composition of the present invention includes both an anionic cleansing surfactant and a nonionic water-insoluble conditioning agent compound, e.g., a silicone or hydrocarbon, the composition is sufficiently phase stable, lathers sufficiently, cleanses the hair and imparts conditioning properties to the hair without a greasy feeling, while maintaining excellent physical and esthetic properties for consumer appeal.
Therefore, the present invention relates to a conditioning shampoo composition for cleansing the hair and for imparting improved physical and cosmetic properties to the hair, such as improved combing properties, luster and manageability. It is known that anionic surfactants are suitable for shampooing the hair, and that certain water-insoluble nonionic compounds are useful for conditioning the hair. In addition, combining an anionic cleansing surfactant and a nonionic water-insoluble conditioning agent in a conditioning composition has proven difficult because of the phase instability resulting from the water-insoluble conditioning compound. In accordance with an important feature of the present invention, anionic surfactants can be combined with a water-insoluble nonionic conditioning agent, like a silicone or a hydrocarbon conditioning compound, to provide a stable and effective conditioning shampoo composition. As manufactured, the composition is metastable, wherein the term "metastable composition" is defined as a composition that is sufficiently stable to resist phase separation during storage; but, upon application to the hair, deposits a sufficient amount of water-insoluble conditioning components onto the hair shaft to withstand rinsing from the hair during the shampooing and rinsing process, and thereby impart conditioning properties to the hair.
Accordingly, the present invention is directed to a conditioning shampoo composition, including a nonsubstantive and high-foaming anionic cleansing surfactant and a combination of an anionic emulsifying surfactant and a nonionic water-insoluble hair conditioning component, that simultaneously cleanses the hair and imparts desirable physical and cosmetic properties to the hair. After shampooing the hair with the conditioning shampoo composition of the present invention, the hair is combed easily when wet and the hair possesses satisfactory cosmetic properties when dry, including, in particular, elasticity, body, sheen and manageability. In contrast to prior compositions, wherein cationic conditioning compounds were blended primarily with amphoteric surfactants, the conditioning shampoo composition of the present invention includes a nonionic, water-insoluble conditioning agent; an anionic emulsifying surfactant; and an anionic cleansing surfactant to cleanse the hair. Surprisingly, the particular class of anionic emulsifying surfactant utilized in the present invention, in conjunction with the polyhydric compound, effectively emulsifies the water-insoluble conditioning agent, thereby precluding phase separation, and in addition, assists the anionic cleansing surfactant cleanse the hair. Therefore, the stability and incompatibility problems normally encountered when a water-insoluble conditioning agent and anionic surfactant are present in the same aqueous composition have been overcome.
The need for stable shampoo compositions that also condition the hair, e.g., renders the hair more manageable, has long been recognized in the art. The present invention is directed to such a stable conditioning shampoo composition, wherein the aqueous composition includes an anionic cleansing surfactant; a water-insoluble hair conditioning agent, like a silicone compound or a hydrocarbon compound; an emulsifying composition comprising a polyhydric compound and an anionic emulsifying surfactant depicted by the general structural formula (I): EQU R.sub.1 --O--(A).sub.x --CH.sub.2 --Y.sup.- M.sup.+, (I)
wherein R.sub.1 is an alkyl or an aralkyl group including about 6 to about 22 carbon atoms, A is an alkylene oxide moiety wherein the alkylene group includes one to about four carbon atoms, x is a number in the range of 4 to about 50, Y is sulfate, sulfonate, carbonate or carboxylate, and M is selected from the group consisting of hydrogen, an alkali metal, an alkaline earth metal, ammonium, an alkylammonium or a hydroxyalkylammonium, wherein the alkyl group includes one to about four carbon atoms; and a suspending agent, wherein the conditioning shampoo composition effectively resists phase separation and effectively delivers the water-insoluble conditioning agent to the hair.
A composition of the present invention is sufficiently stable to resist phase separation, yet is able to impart conditioning properties to shampooed hair, even though a water-insoluble conditioning agent is present in the aqueous composition. The composition demonstrates an excellent ability to deposit the water-insoluble conditioning agent on the hair because the emulsified water-insoluble conditioning agent is present in the composition in a particle size that is sufficiently large to deposit on the hair, yet is sufficiently small to resist phase separation. Therefore, and in accordance with the present invention, the hair is cleansed and, essentially simultaneously, hair conditioning properties are imparted to the hair by a method of contacting the hair with an aqueous composition comprising an anionic cleansing surfactant, a water-insoluble conditioning agent, an emulsifying composition including a polyhydric compound and an anionic emulsifying surfactant depicted by general structural formula (I), and a suspending agent. The stable composition results from both the particular ingredients included in the composition and the method of preparing the composition. The composition of the present invention both cleanses the hair and conditions the hair to provide more manageable and esthetically-pleasing hair in a single application of the shampoo-conditioner composition to the hair.